Re: [osg-users] Impostors

Robert Osfield wrote:

> On Wednesday 05 January 2005 10:34, Ruben wrote:
>
>> Each cell of the grid has two geometries, one with all the fronts
>>grouped, and another one with the roofs, because both have different
>>texture.
>
>
> Could you combine the roof and front textures so you combine the goemetris?

        Not, because the roof is mapped with the complex terrain texturing
system. But anyway, the times that I gave are without the overhead of
texturing roofs (opened with osgviewer directly).

>>I've only the times for 7000 buildings:
>
>
> How many geometries do you actually have for all these buildings?

        570, half for the fronts and half for the roofs.

> The draw time is pretty high, this is for all houses in view?

        In every case, there are LODs that cull the cells at 7 Km, with the
model being 10 Km in length.

> Have you tried using VBO?

        I've just tried, it cuts down draw time in 35%, very impressive, but
not enough yet. Anyway, it will help a lot, thanks.

> Have you made sure that the geometries are well tri-stripped and using index
> primitives, sharing vertices where possible?

        We can't use tri-strips in 90% of the fronts, only separated quads,
because the most common case in buildings is to have sharp corners that
can't share normals. But we have two times each vertex, which could be
solved by using indices, it may enhace even more the performance. I will
test this.

Thanks.
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Received on Wed Jan 5 02:20:01 2005